In the operation of computer systems, particularly systems such as servers and desktop computers, a network controller may be utilized to route traffic to devices, including a management controller. The system may include the operation of an Ethernet connection. In a common operation, the management controller's MAC (Media Access Control) address is used as the MAC address on the network, and this address thus will be used to direct traffic to the management controller via the network controller.
However, the conventional use of the MAC address may limit the operations possible for a network controller by limiting how management controllers may be addressed, particularly when the network connection is shared by more than one management controller, and when the network connection is shared between the management controllers and the host computer system. In protocols such as DHCP (Dynamic Host Configuration Protocol), the IP (Internet Protocol) address of a device is associated with the MAC address for the device, which thus implies that supporting multiple MAC addresses will also require multiple supporting IP addresses. In a modern IPv4 (Internet Protocol version 4) computer environment, IP addresses can be a scarce commodity, particularly in large corporations and other organizations, and thus the support of multiple MAC addresses would consume additional IP addresses from this scarce resource. It is common for management controllers to incorporate their own built-in Ethernet network controller MAC logic. A management controller is not capable of being directly connected to a network and addressed individually without having its own MAC address, and consequently individually accessing management controllers with IP will require each management controller to have at least one unique IP address.
In addition, the distribution and assignment of IP addresses may require significant effort on the part of customers. Customers often have a strong desire to minimize the difficulty in assignment and management of fixed IP addresses, and thus would prefer to limit the number of fixed IP addresses that are required. However, dynamic IP addresses may not provide a viable option because it is often desirable to utilize fixed IP address assignments for important systems such as servers.
It is common practice in network installations to partition IPv4 networks into subnets to facilitate IP packet routing. Within the subnet, devices share a common fixed upper portion of their IP address while their unique IP address is assigned from a combination of the fixed portion and a variable portion of the address. The size of the fixed and variable portion of the address is described by a value called the subnet mask. In a typical implementation, the subnet mask indicates the variable portion of the IP address is 8 bits. This limits the ability to assign IP addresses to systems on the subnet to at most 256 unique addresses. In an existing installation the subnet may already have more than half that number of systems present on the subnet, each consuming one IP address. If the system is replaced with a system that requires two IP addresses, the subnet would not have the capacity for supporting the required number of addresses, and thus the installation would need to either move systems to other subnets or change the subnet mask size. In turn, this would typically require rewiring or reconfiguring the network.
Thus, if a system that only requires a single IP address is to be replaced by a system that requires multiple IP addresses, the ability to introduce the system can be limited by the addressing capacity of the existing subnet. This situation may be aggravated when multiple management controllers, each having its own MAC address, must be accessed.